In the conventional image forming apparatus, a pair of guides are provided in a frame of the apparatus so as to guide the parts protruding outwardly from both left and right sides of the photosensitive member cartridge, i.e., rotation shaft of the photosensitive drum. Further, a pair of grooves are provided on the photosensitive member cartridge so as to guide the developing roller shaft of the developing cartridge into a unit accommodating part which accommodates the developing cartridge. In addition, Japanese Patent Application Publication No. 2003-84645 discloses an image forming apparatus which includes a developing cartridge removable without removing the photosensitive member cartridge from a frame.
In the above apparatus, a user is usually required to pay attention to attachment and detachment of the developing cartridge with respect to the photosensitive member cartridge.
An object of the present invention is to provide an image forming device in which a developing cartridge is easily attached to or detached from a photosensitive member cartridge loaded in a main casing.